Weird problem, woke up and box was off ? Had to unplug

2nd day of use. Went to bed with the Zidoo left on the Media Center, so just turned my TV off. Today I wake up and the front display is off and only a blue light is on for the power. Nothing on TV. Tried turning on with my remote, but nothing happened, nor when pressing power on front of box. Could only get it on when unplugging and replugging it from the power. Any ideas what happened ? As I say this is my 2nd day so not left it on before, so will this happen every night ?

EDIT : Just seen in the latest 1.4.6 (which I didn't have installed until just now) update something being fixed about USB3 devices being plugged in and box not waking when attached. I have a USB3 device attached. Could this be why ?